docs: def update_namelist_file(self, rapid_namelist_file,
                               new_namelist_file=None):
          """
          Update existing namelist file with new parameters
  
          Parameters
          ----------
          rapid_namelist_file: str
              Path of namelist file to use in the simulation. It will be
              updated with any parameters added to the RAPID manager.
          new_namelist_file: str, optional
              Path to output the updated namelist file.
          """
          if os.path.exists(rapid_namelist_file) and rapid_namelist_file:
              log("Adding missing inputs from RAPID input file ...",
                  "INFO")
              with open(rapid_namelist_file, 'r') as old_file:
                  for line in old_file:
                      line = line.strip()
                      if not line[:1].isalpha() or not line:
                          continue
                      line_split = line.split("=")
                      attr = line_split[0].strip()
                      value = None
                      if len(line_split) > 1:
                          value = line_split[1].strip()\
                              .replace("'", "").replace('"', "")
                          # convert integers to integers
                          try:
                              value = int(value)
                          except ValueError:
                              pass
                          # remove dots from beginning & end of value
                          if attr.startswith('BS'):
                              value = value.replace(".", "")
                      # add attribute if exists
                      if attr in dir(self) and not attr.startswith('_'):
                          # set attribute if not set already
                          if not getattr(self, attr):
                              setattr(self, attr, value)
                      else:
                          log("Invalid argument {0}. Skipping ...".format(attr),
                              "INFO")
  
              if new_namelist_file is None:
                  new_namelist_file = rapid_namelist_file
  
              self.generate_namelist_file(new_namelist_file)
          else:
              log("RAPID namelist file to update not found.",
                  "ERROR")